1. Field of the Invention
The present invention relates to a cutting tool for use in a milling machine and more particularly, to a ball nose end cutting tool particularly adapted for a copy milling machine, which includes one unit of a cutting bit having a pair of cutting edges disposed in a diagonal line with respect to each other for minimizing cutting stresses being applied to the cutting bit and extending the life span of the cutting tool.
2. Description of the Prior Art
Various types of cutting tools are known in the art. Such prior art cutting tools for use in milling machines can be classified in two categories. One category includes a pair of radial cutting edges fixed to a body made of a strong harness material, by welding with silver and lead as shown in U.S. Pat. No. 4,470,733 to Marques, Jr., and the other category includes a pair of tips fixed to a body by screws as shown in U.S. Pat. No. 4,525,110 to Stojanovski and U.S. Pat. No. 4,527,930 to Harroun.
However, these cutting tools suffer from a number of problems such as, for example, (1) since two tips are connected to each other and the gap formed between both tips is welded by silver, sometimes there is no cutting edge disposed on the center point portion of the cutting tool; (2) since the center point portion of the cutting tool as described above is subjected to cutting stresses and vibration during operation thereof, the welded portion can easily be cracked; (3) since bolts are used for fixing the tips to the body, a space can form between the tips and the body such that the bolts can become loosened during operation thereof, and the cutting edge does not retain its exact ball-shaped configuration; and (4) since the prior art cutting tools exhibit the above problems, they have a short life span.